I am all for open source and would love to take the plunge on your upcoming phone, but some banking apps just aren’t open source (like Revolut) and they are vital for my company and my private life. Will I be able to use those on the Librem 5?

From discussions in the community/librem-5 Matrix chat room it seems that at least one developer in the community is working on a libre banking app. There may also be others. It may be worth getting in touch with them and seeing if their app would meet your needs.